The Conservatives must embrace their traditional ideology and abandon the search for the centre ground, Lord Saatchi said last night, in a thinly veiled attack on David Cameron's strategy.

The former Tory co-chairman said that politicians were in thrall to the "dinner party myth" that elections could be won only from the centre - and failed to realise that the result was a "super-cynical electorate". He urged conservatives on both sides of the Atlantic to "man the ideological barricades".

Mr Cameron, who visited Sudan yesterday to meet refugees fleeing the violence in Darfur and United Nations and African Union officials, warned earlier this year that politicians who stuck rigidly to ideology were courting disaster.

Lord Saatchi is the latest in a string of Thatcherite grandees to question the Conservative leader's attempts to reposition the party. Rightwing Tories are particularly keen to see a commitment to slash taxes and many are disappointed that the shadow chancellor, George Osborne, did not give a warmer welcome to Lord Forsyth's proposal for cuts.

Lord Lamont warned in the summer that the party needed "more policies, more quickly", while another former chancellor, Lord Lawson, said recently: "There is a strong case for saying what you think is right, giving the public a strong sense of direction."

Lord Saatchi, who masterminded the marketing of the Tories in the 1980s and was co-chairman from 2003 until 2005, told BBC Radio 4's PM programme that Mr Cameron had done "brilliantly" as leader.

But in a pamphlet published yesterday, In Praise of Ideology, he said people were losing faith in politics because there was so little difference between the parties. "The pragmatism of the centre ground turns politics into a commodity market - because pragmatism leads to opportunism, which leads to cynicism. People can spot a left/right 'positioning exercise' a mile off. The motive for these moves is too transparent. Voters always suspected that politicians would 'say anything to get elected'. Now they know it's true."

He said the failure of many young people to vote was a rational reaction, but suggested Conservatives could win back support by championing freedom and responsibilities of the individual. He added: "Without ideology, political discourse is reduced to claim and counterclaim about actual 'delivery'. But in that arena ... there is only one winner: neither."

He urged Conservatives to be proud of their economic stance, repeating one of Mrs Thatcher's most famous remarks,saying: "Conservatism believes that 'caring that works costs cash' - the Good Samaritan showed that first you need the money in order to do the good works'."

Yesterday Mr Osborne focused on a less traditionally Tory area of policy, as he set out plans to tackle financial exclusion and encourage banks and credit providers to demonstrate greater social responsibility at a debt summit in London.